<!DOCTYPE>
<html>
<head>
	<title></title>
	<meta charset="utf-8"/>
	<style>
		*{margin:0;padding:0;}
		#main{
			width:60%;
			height:100px;
			border:1px solid red;
			margin:0 auto;
		}
		#left{
			float:left;
			width:30%;
			height:100px;
			background:red;
		}
		#right{
			float:right;
			width:30%;
			height:100px;
			background:yellow;
		}
		#middle{
			float:left;
			width:40%;
			height:100px;
			background:blue;
		}
	</style>
</head>
<body>
	<div id="main">
		<div id="left"></div>
		<div id="middle"></div>
		<div id="right"></div>
	</div>
</body>
</html>